JomBadger

Features in backend :

create a badge
create categories for your badges
manage the created elements
create menus to webpages for your visitors (see frontend features)
create organizations
plugin to add a code in your articles to automatically validate a badge, without intervention from webmaster
issue badge for a given email by webmaster
and you can earn your own badge if you install the component and do some actions ;-)

Features in frontend

display a page with all badges you can earn on your website
display the page that issues the badge, for authenticated users
send badge to your backpack
automated badge validation when reading an article

Much more informations in documentation ...